By Theopolis Waters
DES MOINES Iowa (Reuters) - Hog losses on U.S. farms from a deadly virus have slowed, reaching about 8 million head currently after hitting 7 million around February, an economist with a leading pork industry group told Reuters.
Rising temperatures heading into the summer may be a factor, Paragon Economics President and National Pork Producers Council consultant Steve Meyer said at World Pork Expo 2014, as the virus tends to thrive under cold, damp conditions.
There is still no official tally of the number of pig deaths from Porcine Epidemic Diarrhea virus (PEDv), which first appeared in the United States in April 2013 and has since swept through 30 states.
The government has said it will make PEDv reportable, which means cases must be officially registered. Despite millions of dollars spent on research, no one knows how the virus entered the country, and there is no reliable vaccine.
Meyer said the 7 million figure was when about 50 percent of the sows in the United States had been infected.
"I had the 7 million number pretty early, and it was based on data through February," Meyer said. "I didn't realize it had been that static" since then.
The most recent report on deaths is from a University of Minnesota monitoring project and says 58 percent of the sow herds owned by 17 large hog production systems had been infected since PEDv first broke.
The 17 systems are not a random sample, but they represent 2.7 million sows, said Meyer.
Based on the University of Minnesota results, he arrived at the piglet loss figure of 8 million head.
There are about 68,000 U.S. swine production systems, including many small operations. The latest figures put the total hog herd at 62.9 million as of March 1, the smallest for that month since 2007.
The latest U.S. Agriculture Department data showed the number of confirmed PEDv cases at 7,111. The number of cases logged slowed to 142 in the week ended May 25 from 158 the week before and 198 for the last week of April.
Tom Burkgren, executive director of the American Association of Swine Veterinarians, said warmer weather could help, but farmers should retain biosecurity measures to keep the disease from spreading.
"Although we don't want 100-degree days, the virus hates them as much as we do," said Burkgren. "But don't let your guard down."
There are concerns among farmers and the industry that the onset of cooler weather in the fall could trigger another rise in cases of the disease.
PEDv is neither harmful to humans nor transmissible through pork. It has occurred in Europe and Asia, but was first discovered in the United States in 2013.
(Editing by Lisa Von Ahn)